The background of this invention herein is substantially the same as the background of the invention of the referenced patent application. This invention is directed to certain improvements of the invention of the referenced patent application, the primary improvement being that instead of the belt being guided around the peripheral segment of the toning roller which it engages by means of pressure being applied through the belt by guide rollers, the guide rollers are sufficiently spaced from the toning roller so that there is a freely stretched and unsupported portion of the belt on opposite sides of toning roller. Thus, the toning roller is restrained by the belt alone thereby enabling accurate control of belt tension.
The toner carried by the toning roller into the nip formed between the toning roller and the converging exterior surface of the belt is a more or less wedge-shaped mass that starts to tone the latent image before it is compressed as it passes over the peripheral segment of the toning roller which is closely engaged by the belt. This is believed to give a better effect enabling greater densities of toning to be achieved.
An important advantage of the arrangement is that any departure from parallelism between the shafts of the toning roller and the guide rollers or between the outer surfaces of the rollers is compensated for by the flexibility of the belt. This is because there is a free, unsupported section of the belt on opposite sides of the toning roller. Even flexing of the rollers because they are supported at their ends and subjected to tension of the belt is to some extent compensated for.
Another advantage of the present arrangement is that the locations and dimensions of the guide rollers are not critical relative to the toning roller and the toning station thereby enabling simple and more convenient configurations of the belt and its guiding and driving rollers.